This invention relates to a new catalyst made by a modification of the methods described in Pullukat et al. U.S. Pat. No. 3,780,011 which is assigned to the assignee hereof. The modification comprises the thermal activation step. In the method of U.S. Pat. No. 3,780,011 a catalyst is made by the addition of an alkyl ester of titanium to a dry, intimate mixture of chromium oxide and a support such as silica, followed by activation in a dry gas containing oxygen. The new catalyst of this invention can be made by following this method except that after the addition of the titanium ester the composite is given two separate thermal treatments. The first thermal treatment is in an inert or reducing (non-oxidizing) gas and the second is in an oxidizing gas such as air. This invention is also an extension of U.S. Pat. No. 3,780,011 in that the modified catalysts of this invention can be made from various chromium compounds.